Guanine tetrad

See also: G-quadruplex
Left: A guanine tetrad featuring a central cation
Right: Three guanine tetrads contributing to the structure of a G-quadruplex

In molecular biology, a guanine tetrad (also known as a G-tetrad or G-quartet) is a structure composed of four guanine bases in a square planar array.[1][2] They most prominently contribute to the structure of G-quadruplexes, where their hydrogen bonding stabilizes the structure.[3][4] Usually, there are at least two guanine tetrads in a G-quadruplex, and they often feature Hoogsteen-style hydrogen bonding.[1]

Guanine tetrads are formed by sequences rich in guanine, such as GGGGC.[5] They may also play a role in the dimerization of non-endogenous RNAs to facilitate the replication of some viruses.[5] Guanine tetrads dimerize through their 5' ends since it is more energetically favorable.[6]

They can be stabilized by central cations, such as lithium, sodium, potassium, rubidium, or caesium.[7][8] However, they still form a variety of different structures.[1] Guanine tetrads are not always stable, but the sugar-phosphate backbone of DNA can assist in stability of the guanine tetrads themselves.[1] Guanine tetrads are more stable when stacked, as intermolecular forces between each layers help stabilize them.[9]

Guanine tetrads can also influence recombination, replication, and transcription.[1][2] For instance, guanine tetrads are found in the promoter region of the Myc family of oncogenes.[10] They also function in immunoglobulin class switching and may play a role in the genome of HIV.[11] Guanine tetrads appear frequently in the telomeric regions of DNA.[3]

  1. ^ a b c d e Cite error: The named reference Molecular dynamics simulations was invoked but never defined (see the help page).
  2. ^ a b Cite error: The named reference MyoD binds to the guanine tetrad was invoked but never defined (see the help page).
  3. ^ a b Cite error: The named reference Telomeric DNA dimerizes was invoked but never defined (see the help page).
  4. ^ Cite error: The named reference Are Guanine Tetrads Stabilized was invoked but never defined (see the help page).
  5. ^ a b Cite error: The named reference Guanine tetrad and palindromic was invoked but never defined (see the help page).
  6. ^ Cite error: The named reference Why do G-quadruplexes dimerize was invoked but never defined (see the help page).
  7. ^ Cite error: The named reference Guanine tetrads: an IRMPD spectroscopy was invoked but never defined (see the help page).
  8. ^ Cite error: The named reference Theoretical study of incorporating was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference Guanine Base Stacking was invoked but never defined (see the help page).
  10. ^ Cite error: The named reference Small-molecule interaction was invoked but never defined (see the help page).
  11. ^ Cite error: The named reference The High-Resolution Crystal was invoked but never defined (see the help page).